Many different types of grippers for picking up, transporting, and unloading of semiconductor products, such as semiconductor wafers, wafer substrates, wafer spacers, etc., are known and used in the semiconductor production industry. Such devices are also known as end effectors which can be attached to the end of the mechanical arm, e.g., of an industrial robot. Roughly such devices can be divided into mechanical grippers, vacuum grippers or chucks, or combined vacuum-mechanical devices.
For example, U.S. Pat. No. 6,015,174 discloses an end effector system adapted to be used for robotic tooling applications which allow the end effector to be used to acquire parts by vacuum pick-up or grasping. A vacuum type end effector is provided at the end of each of two robotic tooling fingers. Each vacuum type end effector includes a flexible bellows member on the end thereof such that it can be used for vacuum acquisition. Extending down from each finger to reside adjacent a respective bellows is a pinch member. Through robotic control of the movement of the fingers, finger gripping can be accomplished to grip an object between the two bellows using the pinch members for lateral support. As the part is captured between the two bellows, each bellows is compressed against its respective pinch member. In this manner, the bellows are at least partially collapsed such that a vacuum sensor located in the vacuum supply line to the bellows registers that a vacuum is present and, thus, a part has been acquired. That same vacuum sensor allows the robot to know when a part has been acquired by the bellows in the typical vacuum-type pick-up arrangement.
U.S. Pat. No. 6,893,070 discloses an integrated robot end effector for use in a robotic manufacturing environment. The integrated robot end effector generally includes a circular body having a generally circular rim on an edge thereof. The integrated robot end effector also includes a plurality of orifices through a surface of the body. A plurality of ports extend through a predetermined section of the rim or body of the integrated robot end effector. A plurality of grooves in a surface of the body connects the orifices to the ports within the robot end effector. A cover is secured to the rim of the robot end effector by a retainer. The robot end effector internalizes and integrates all external lines servicing associated vacuum cups or grippers located on the outer surface of the robot end effector.
U.S. Pat. No. 4,451,197 discloses an object detector which incorporates a photoelectric detector in the vacuum flow path of a vacuum pickup system to serve as a device to determine whether an object has been successfully engaged, retained and transported by a vacuum orifice, so that transport cycles may be modified or terminated by control circuitry in the event that the object has not been successfully engaged, retained and transported, thereby saving time and reducing damage to object, transport means or the surface to which the object is transported.
US Patent Application Publication No. 20030052495 published in 2003 discloses a multiple vortex chucks for supporting a wafer. Vortex chucks are located along the periphery of the end-effector to help prevent a flexible wafer from curling. The end-effector has limiters to restrict the lateral movement of a supported wafer. In one example, the end-effector has a detector for detecting the presence of a wafer. The detector is mounted at a shallow angle to allow the end-effector to be positioned close to a wafer to be picked-up, thereby allowing detection of deformed wafers contained in a wafer cassette. The shallow angle of the detector also minimizes the thickness of the end-effector. Also disclosed is a wafer station with features similar to that of the end-effector.
U.S. Pat. No. 3,147,017 discloses a vacuum-actuated chuck for gripping annular workpieces, in which a vacuum-actuated piston-like element acts upon the workpiece to maintain the workpiece advantageously gripped and supported on the chuck. However, while the piston-like element of the chuck does provide for a certain amount of mechanical gripping of the workpiece, substantial gripping action is achieved through the application of vacuum to the workpiece.
European Patent Application Publication No. EP 0902966 WO1997045862A1) (discloses a holder for wafer-like articles. The holder comprises a platform having a wafer-like article facing surface that includes at least one annular groove therein. The annular groove has a ceiling surface therein which is provided with an opening. A gas conducting conduit is connected to the opening. A gas, which introduced into the conduit, exits the conduit through the opening. By choosing a particular orientation of the conduit relative to the annular groove, the gas exiting the opening can be caused to circulate in a clockwise or counter clockwise fashion. The circular flow of gas causes the formation of a vortex adjacent to the article facing surface. A wafer-like article may be held in a suspended state adjacent to the wafer-like article facing surface without contact by the vortex and the gas flowing between the wafer-like article and the article facing surface.